Questions on unit 1
Lesson 3
I. Complete the following statements:
1. The smallest part of the element that takes apart in a chemical reaction is knownas atom
3. The symbol of carbon atom is C while that of calcium atom isCa
4. The symbol of nitrogen atom is N while that of neon atom is Ne
5- Nais the symbol of sodium atom, while that of sulphur atom isS
7. The nucleus of the atom contains two different types of particles, these are protons and neutrons
8.The atom consists of nucleus andelectrons
9. In the nucleus, there are positively charged particles called protonsand neutralparticles calledneutrons
10. The mass of the atom is concentrated in the nucleus because the mass of electronisnegligible if it is compared to the mass of
Protonsor neutrons.
11.Electrons havenegative charge, while protons have positivecharge.
12.Electrons revolve around the nucleus in energy levels,where each one of them has its own energy
13. The number of neutrons in the nucleus of an atom may be equal to or greater than thenumber of protons
14. The atom is electrically neutral because the number of protonsin the nucleus is equalto the number of electrons
15. The sum of the numbers of the protons. and neutrons in the nucleus is known as mass number
II. Write the scientific term for each of the following:
1. The fundamental building unit of matter that can take apart in the chemicalReaction. atom
2. The positively charged particle in the nucleus of an atom. protons
3. The number of positively protons in the nucleus. Atomic number
4. Neutral particle exists in the nucleus of an atom. Neutrons
5. Negatively charged particles of negligible mass that revolves around the nucleus. Electrons
6. A part of an atom exists in its center. Nucleus
7. The number which is written at the bottom left side of the element symbol. Atomic number
8. The number which is written at the top left side of the element symbol. Mass number
9. The difference between the mass number and the atomic number. Number of neutrons
10. The sum of the numbers of protons and neutrons in the nucleus. Mass number
III.Put (√) in front of the right statement and (x) in front of the wrong one and correct it :
1. The molecule is the smallest part of the element that can take apart in thechemical reaction without changing. ( X )
The atom
2. (He) is the symbol of hydrogen element, while (H) is the symbol
of helium element. ( X )
( H ) - ( He )
3. The symbol of zinc is (Zn), while (Si) is the symbol of sulphur.
( X) (S)
4. (Fe) is the symbol of iron.
5. The atom is electrically charged, while its nucleus is electrically neutral. ( X)
Neutral – positively charged
IV. Give reason for:-
- the atom is electrically neutral.
-Because the number of positive protons equal number of electrons .
- the mass of the atom is concentrated in the nucleus.
-Because the mass of electrons is negligible relative to the mass of protons and neutrons
- the electrons are distributed to fill the (K) level before filling the (L)level.
-Because the k level has lower energy than L level
- hydrogen molecule is diatomic, while helium molecule is mono-atomic.
-Because hydrogen consists of 2 atoms while helium consists of 1 atom
- noble (inert)gases molecule are mono-atomic.
-Because inert gases consist of 1 atom
V. Write the name of the elements of the following symbols:
1. H 2.He 5 .Cl
8.K 9.Na 10. Cu 11.Br
See p.24
VI. Write the electronic configuration of the following:
, , , ,
Electronic config. In H K 1
He K 2
F K 2
L 7
Ne k 2
L 8
Na K2
L8
M1
Then find:
1-Number of electrons in the outer level.
H=1, He=2, F=7, Ne=8, Na=1
2-The number of neutrons in each atom.
H=1-1=0,He4-2=2, F=18-9=9, Ne=20-10=10, Na=23-11=12
3-the atomic numberH=1,He=2, F=9, Ne=10, Na=11
4-the mass number H=1, He=4, F18, Ne=20, Na=23
5-Are those elements active or not.
H, F, Naare active the rest are inactive
VII. Write the symbols of the following element:
1)Sodium Na
2)Potassium K
3)Chlorine Cl
4)Nitrogen N
5)Calcium Ca
6)Aluminum Al
7)Phosphorus P